Well, obviate came up recently as a wotd, and I just couldn't get enough of words with a "b", ever since the silent "b" of ostensible.
Obviate comes from the Latin "obvius" for "against" "the way", but colloquially meaning "that is in the way; that goes against" which got conjugated into "to act contrary to; go against" for the act of the person rather than the physical placement of a person or thing. However, by the time of the Renaissance, the word then came to mean "to meet and do away with". So, how and why did the perspective of the word change from describing the impediment to getting rid of the impediment, for which DD is completely inadequate on this point. OED's entry may shed some light on this. Apparently, there is an obsolete [I'll get to this word later!] definition which means "to meet, encounter; hence to withstand, oppose (a person or thing)," consistent with the idea that meeting someone or something inherently in your way was acting against by withstanding or opposing this person or thing. A second usage evolved contemporaneously to this obsolete usage then that the act of meeting the obstacle [another word I'll get to later] was "to meet and do away with" the obstacle, and then rather than wait to meet the obstacle, the word's meaning evolved further to prevent the anticipated obstacle. So, we can see the rather straightforward expansion of the word, but in no way does it really mean with it's etymological roots suggest.
As for usage, this is a great word, but like clarion, has a particular catch phrase usage. Obviate the need or obviate a need. The anticipated closings due to snow may obviate a need to call in sick. However, unlike clarion, the word can be used without sounding odd alone. The video tape corroborating the defendant's alibi obviated all doubt as his credibility. It should be noted that obviate now as a preventative of the obstacle means that it will completely remove the obstacle, not merely mitigate or lessen. In fact, you might hope to mitigate the effect of an obligation you could not obviate, such as a family dinner. And as a preventative now, obviate works with abstractions which are based on perception/thought (duties, needs, tendencies) (his new medications obviated his thoughts of suicide) and still with the conduct which was in opposition (her co-counsel's offering to write the opposition to Plaintiff's emergency motion to compel obviated her having to stay late; Plaintiff's acceptance of the offer of settlement obviated the trial). Furthermore, the obstacle doesn't need to be so onerous or thorough as it once meant as long as the obstacle is perceived to be contrary to an implied desired action. So, perhaps Plaintiff's acceptance of the offer of settlement unfortunately obviated the trial since she was confident she could secure a defense verdict. That the conductor was not too familiar with the music to give appropriate cues obviated the chorus' from the need to memorize the piece. The usage is correct, although the sentiment is not. Sometimes is it more useful to memorize such music in order to deal with a tentative conductor. But I still tend to use obviate with a need, and reserve verbs which are more simply understood alone, such as exonerate, alleviate or just plain remove, and as for the family dinner obligation, that would be a stay of execution.
Now, obfuscate just sounds great, with all those consonants! It does not roll trippingly off the tongue, and in not doing so, it draws the attention of the listener, just as the people who have trouble saying it also draw the attention of the listener. So, practice this word at home before you try it in public. Similarly, in writing, it looks odd (that "bf" combo) that is also stands out, like a possible typo.
Anyway, back to the word. Obfuscate comes from the Latin "obfuscare" for to darken over. There still is a retained meaning of simply "to darken", but I can hardly ever believe I would say "Let's obfuscate the room, honey" or "the recent power outage obfuscated entire city blocks" or even "on a sunny day, only the clouds can obfuscate the hills". It's just too odd, although I will note that since obfuscate has that preposition of "over" from the original Latin, any use of "to darken" must be darkening by covering or making opaque so light cannot pass, therefore, only the last usage is really correct. Obfuscate the parrot cage for the evening. Obfuscate the light bulb by adding a lamp shade. But in the nature of darkening, as it covers or opaques something from view, obfuscate has taken on a meaning of covering or opaquing intangibles from understanding, and then finally covering or opaquing an individual from understanding. He successfully avoided the speeding ticket by obfuscating the officer in a lengthy explanation of his mother's illness which he just got the phone call from his ex-wife while he was at his daughter's piano recital... But I don't prefer that usage, since I don't really associate obfuscate with confusing people as much as with burying an idea that one does not want to be know. He successfully avoided the speeding ticket by obfuscating his need to get to the beach in a lengthy explanation of his mother's illness... That's better. I was never able to obfuscate my grandmother into thinking I hadn't had the candy. Maybe, in a pinch, although dupe is better. I was never able to obfuscate my fiendish designs to garner another piece of candy in the veil of innocent. Perhaps a bit too poetic, but passable. Plaintiff's counsel tried to obfuscate the judge of his client's weak case by arguing the equity rather than the law. Yes. And this is where I tend to use this word, and have heard this word used. So, second usage only for me as we try to obfuscate inconsistent theories, lame excuses, guilt, blame... You get the picture. Works like a charm, perhaps because the word obfuscate tends to obfuscate people.